The Determination of the Tidal Variations of the Plumb Line and the Nearly Diurnal Free Wobble from the PZT Observations

Abstract

The optical astrometric observations contain beside the information on the Earth rotation parameters (polar motion, changes of the Earth’s rotation) also the information on other geodynamical events. There are the tidal influence on the Earth’s mantle, the influence of the inner construction of the Earth on the space motion of the rotational axes. We have tried to determine some of the events from the observations made on the PZT at Ondřejov Observatory during the years 1973–1990. We have modified slightly the least-square method for simultaneous estimation of corrections for star places, proper motions and short periodic latitude-longitude variations (Manabe et al., 1977). Also (Hefty, 1989) dealt with the similar problems aiming at the nearly diurnal free wobble by using the group results of the PZT at Ondfřejov.KeywordsProper MotionPolar MotionPlumb LineShort Periodic TermTidal FrequencyThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.